A typical form of procedure for balancing a motor vehicle wheel unit comprising the wheel itself such as a disk wheel and a pneumatic tire carried thereon provides that the vehicle wheel is clamped on a measuring spindle of a balancing machine and the geometrical data of the vehicle wheel are sensed by means of a sensing device and stored. At least one measuring run is effected for ascertaining unbalance of the vehicle wheel and for determining at least one balancing vector, involving evaluation of measurement signals outputted by measurement value sensors and the geometrical data of the wheel, in dependence on a set balancing program. At least one balancing weight is fixed to the vehicle wheel to compensate for the unbalance which is ascertained in that way.
A method and an apparatus of that kind are to be found in DE 42 29 865 C2.
Conventional balancing machines, for example Geodyna 5000 or Geodyna 5500, see the prospectus from Hofmann Werkstatt-Technik GmbH, Pfungstadt, Germany, imprint 9502101 03.94, have various balancing programs. The positioning of the one or more balancing weights on the disk wheel can be determined by means of such balancing programs. Usually there is a standard program for disk wheels consisting of steel and five selectable balancing programs for disk wheels comprising light metal or alloy, for example aluminum.
It will be noted at this point that the term light metal is used herein to denote wheels made of a light metal or a light metal alloy, for example aluminum, aluminum alloy or the like.
That ensures that, depending on the type of disk wheel involved, the balancing weights are positioned on the wheel in consideration of the requirements for optimum smoothness of operation and the visual appearance of the wheel, when carrying out the unbalance compensating operation. The choice of the appropriate balancing program is effected in dependence on visual assessment of the motor vehicle wheel by the operator of the machine. In general it is not possible to effect an assessment on the basis of the weight involved because the weight of the wheel is essentially determined by the tire fitted on the disk wheel. In that situation incorrect assessments may occur so that the wrong balancing program is then selected.
German utility model No 1 801 947 discloses a balancing apparatus in which balancing weights which are sorted in accordance with the size thereof, are kept in stock in containers or other storage assemblies. After a measuring run which involves determining the balancing weight that is required for a test body, the appropriate container or storage assembly which contains that balancing weight is identified by a respective marking device in order to make it easier for the operator to have immediate and ready access to the correct balancing weight.
DE 38 03 325 A1 discloses a method of balancing a motor vehicle wheel or the like, in which a stationary wheel which is clamped on to a shaft of a balancing machine is caused to oscillate and thereupon wheel-specific data which are obtained from sensor output signals from electrical sensors coupled to the shaft are compared to stored pattern signals which are characteristic in respect of different disk wheels. That procedure makes it possible to determine the respective type of wheel to be balanced.
U.S. Pat. No. 2,697,345 discloses the use of magnetic test balancing weights when balancing wheels with steel rims. A freely rotatable wheel to be balanced rotates into a given position, by virtue of its unbalance, under the effect of the force of gravity. One or more magnetic test balancing weights are applied to the rim flange to compensate for the unbalance, and then replaced by conventional permanently fitted balancing weights.